In the third year work will concentrate on filling out quantitative data on the various ionic currents of voltage clamped bullfrog ganglion cells, together with their pharmacological characterization. In particular, attention will be directed to tail currents, to determine whether calcium currents really inactivate. Finally, noise and single channel measurements on "M" currents will be made, on cultured sympathetic neurones. This will permit evaluation of single channel lifetime and conductance.